1. Field of the Invention
The present invention relates to a fuel heating system for internal combustion engines and more particularly, but not by way of limitation, to a continuous circulating fuel heating system for raising and maintaining fuel temperature to its vaporization temperature at the introduction to the carburetor.
2. History of the Prior Art
It has long been recognized that increased fuel economy can be realized if the temperature of the fuel, prior to entering the carburetor, can be raised to its vaporization temperature so that upon encountering the low pressure in the carburetor barrel, it completely vaporizes providing more complete combustion and, hence, providing more efficient power conversion.
Since it is necessary to keep such heated fuel systems under pressure to maintain the fuel in the desired liquid state prior to entering the carburetor, the previous systems include a fuel pressure regulator interposed in the line connecting the hot fuel supply to the carburetor as taught in the patent to Furr et al, U.S. Pat. No. 4,083,340, issued Apr. 11, 1978 and entitled "Gasoline Superheater."
The primary disadvantage to such systems is that they are unable to adjust to different fuel flow rates needed when changing engine speed and, hence, fuel demands.
For example, when the engine speed is high or under laboring conditions, the fuel flows rapidly through the regulator providing heated fuel to the carburetor. However, during slow driving or idle when the engine is not laboring, fuel demand is less and fuel therefore backs up in the line between the pressure regulator and the heat exchanger and, hence, cooling occurs. Then when high fuel demand resumes, this cooled fuel is supplied to the carburetor shortly thereafter followed by superheated fuel which causes the mixture to be constantly fluctuating leading to inefficient and rough engine operation.
Further, if the superheater of the Furr et al patent is properly sized for typical fuel consumption, it may be inadequate during periods of great fuel demand.